From everything I can find, you basically have an iPod Touch. I quickly scanned all the phone hacking forums I frequent and they all point out the same thing, different frequency chipsets.
3G on an iPhone with TMobile is out of the question.
I don't want to go to a TMobile store because they will make me sign up for a smartphone data plan. Although the iPhone is a smartphone, since it won't run at smartphone speeds, I see no need to spend $20+ per month for than when their Web2Go EDGE plan is $5 to $10 per month.